Milk consumption was evolutionarily favored in humans due to a lack of defense chemicals and genetic adaptations like lactase persistence.

“even though they're both foods that are relatively new in the human diet there's lots of good evidence that milk doesn't contain these defense chemicals like seeds do and there are genetic adaptations in the human genome specifically the lactase persistence Gene which I'll talk about shortly that suggests that consuming milk was an adaptation that was favored in human health and evolution”